Biden has spoken at the annual House Democratic event in recent years, and he is popular with rank-and-file lawmakers.

House Democrats need a net gain of 17 seats to take back the majority in November, although campaign analysts are already downplaying the possibility of that happening on Election Day. Several high-profile House Democrats, including George Miller and Henry Waxman, have announced they will retire in recent weeks. And while those seats will most likely stay in Democratic hands, their decision to end long congressional careers is being interpreted by Republicans as a sign Democrats can’t win.

Obama’s soft poll numbers and the botched rollout of Obamacare have also hurt Democratic prospects at this point.

Yet Minority Leader Nancy Pelosi (D-Calif.) and the Democratic Congressional Campaign Committee have outraised their GOP counterparts so far. And Democrats hope that the upcoming debt ceiling and immigration reform fights will give them an opportunity to rally their faithful.